\begin{abstract}
Different kinds of models are used to study various natural and
technical phenomena. Usually, the researcher is limited to using a
certain kind of model approach, not using others (or even not
realizing the existence of other model approaches). The authors
believe that a complete study of a certain phenomenon should cover
several model approaches. The paper describes several model
approaches that we used in the study of the random early detection
active queue management algorithm. Both the model approaches
themselves and their implementation and the results obtained are
described.
\keywords{active queue management
  \and
  mathematical modeling
  \and
  simulation
  \and
  surrogate modeling
  \and
  stochastic systems}
\end{abstract}



